This invention relates to a process for reducing the organics content of an aqueous alkaline waste stream containing organic esters having pesticidal properties by acidification and extraction with a C.sub.5 -C.sub.10 hydrocarbon.
Aqueous waste streams containing contaminating amounts of organic compounds are generated in a variety of industrial processes, for example in the manufacture of insecticides. Before such aqueous streams can be discharged into a receiving stream, the organics content must be substantially reduced in order to meet regulatory standards. For example, the production of pesticidally active cyano-substituted carboxylic acid esters e.g. by Francis coupling, may result in an alkaline aqueous waste stream containing not only small amounts of the ester together with dissolved starting materials, but in addition alkali metal salts. These esters have prominent insecticidal and acaricidal activities, but low toxicity to mammals. Disposal of such waste streams e.g. by incineration is both difficult and expensive owing to the presence of the alkali metal salts.